内压容器筒体与大接管相贯区的应力强度评定

Evaluation on the Stress Strength at the Junction Area between the Cylinder of an Internal Pressure Vessel and Its Big Nozzle

针对内压容器筒体开有大直径孔后会产生很高的应力集中这一问题,采用有限元方法计算了具有同一开孔率但有不同接管与筒体直径比的压力容器结构的应力分布,并在应力危险截面选择了5条应力处理线进行了应力强度评定。结果发现,5条应力处理线中处理线c的一次局部薄膜应力分量SⅡ最大;而一次应力加二次应力SⅣ的最大值则随t/T的大小体现在不同的处理线上,故SⅣ的评定应针对各处理线进行。在笔者的算例中,4种t/T结构中只有t/T=1.0的结构可满足应力分析设计准则要求。

The stress distribution of the structure of a pressure vessel with the same opening ratios and different diameter ratios between nozzles and cylinders was calculated using finite element method for the problem that a very high stress concentration would be generated after a big diameter hole was opened on the cylinder of an internal pressure vessel, and five stress treatment lines on the stress danger section were selected for stress strength evaluation. The result shows that the primary local thin membrane stress component So of the stress treatment line c among the five stress treatment lines is maximum; and the maximum value of the primary stress plus secondary stress Sty occurs in different stress treatment lines based on the t/T ratio. Therefore, the evaluation of Sty should be performed for each stress treatment line. In the calculation sample of the author, only the structure of t/T = 1.0 in four structures of t/T can satisfy the criteria demand of analysis and design of stress.